An FDA Early Feasibility Study (EFS) allows ?for early clinical evaluation of devices to provide proof of principle and initial clinical safety data.? Over the past four years, our team has performed the first EFS clinical trial of a percutaneous osseointegrated (OI) docking system for patients with transfemoral amputations. As of December 1, 2017, 10 transfemoral VA patients received the device and are ambulating successfully for up to 22-months with positive safety and functional results. Currently, the EFS safety and functionality data are being used to target a pivotal study of the transfemoral device to obtain Premarket Approval (PMA) that will result in the broad clinical introduction of the transfemoral OI device within the US. However, transhumeral patients are currently underserved by prosthetic technologies. Nearly 60% of transhumeral patients limit their use of suspension-based prostheses and upwards of 30% of upper-limb suspension-type prosthetic devices are completely abandoned by both the VA and the military patient populations?with abandonment of the prosthesis most common among women. The overarching goal of this proposal is to maximize the functional recovery of US veteran, military, and civilian patients with transhumeral limb loss. We believe that this can be done by bringing FDA approved percutaneous OI devices to this patient population. Over the past 3 years, we developed a unique percutaneous OI device, known here as PODS, specifically for transhumeral patients using an evidence based approach. The Primary Aim of this proposal is to perform an FDA guided EFS of the PODS device for transhumeral patients, establishing its initial clinical safety. An initial group (N=20) of transhumeral patients will be recruited to the Salt Lake City (SLC) VA for in-depth consultation and patient centered functional evaluation using a shared decision making approach. Recruited candidates will undergo a full clinical evaluation of the residual limb. Functional assessments, focusing on activities of daily living (ADL), and evaluation of joint and terminal device biomechanics will be collected with their socket-prosthetic device (time = 0). These data will be used for final patient selection (N=10) for inclusion in the FDA EFS clinical trial. The EFS patients will be brought back to the SLC VA, admitted to the hospital, and have the Stage 1 surgery to receive the PODS endoprosthetic device, and then discharged to home. Approximately 4 weeks later, patients will return to the SLC VA and have the Stage 2 procedure performed to place the percutaneous post and attach their prosthetic device. Post- operatively, wound healing will be monitored at the percutaneous site. Patients will be discharged from the hospital to continue outpatient rehabilitation. Periodically (time = 3, 6, and 12 months) following the Stage 2 procedure, patients will be brought back to the SLC VA for assessment of their residual bone, soft tissues and device. The patient centered functional assessments will be repeated with their PODS device at each follow-up visit. Success of the Primary Aim (Safety) will be determined for the 1-year follow-up period with patients successfully using their PODS devices with no device removal due to deep bone infections, aseptic loosening, or atraumatic fracture. The Secondary Aim of this proposal is to use a patient-centered approach to quantify the functional effectiveness of the PODS device, giving specific attention to protocol differences required for male and female patients. Success for the Secondary Aim (Functional Effectiveness) will be to quantify the degree to which patients achieve functional improvement with the PODS device compared to the pre-operative performance. These data will be the first longitudinal analyses to evaluate the impact of percutaneous OI prostheses on objective functionality measures of these transhumeral amputation individuals.